Air curtain



FIG. 1 is a perspective view of the air curtain.

FIG. 2 is a front elevational view thereof.

FIG. 3 is a rear elevational view thereof.

FIG. 4 is a top plan view of the air curtain.

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is an end view on lines 6-6 of FIG. 4. 

CLAIM The ornamental design for an air curtain, as shown and described. 